Collaborative Research: Probing Galaxy and Cluster Halos Using Dwarf Galaxies

University Of Arizona, Tucson AZ

Investigators

Abstract

Drs Mateo and Olszewski will measure the motions of stars within dwarf galaxies, using a spectrograph at the Magellan telescope built by Dr. Mateo. These least-luminous of the galaxies appear to contain far more mass than is present as stars: we observe those stars to be moving so rapidly that they would escape from the galaxy if not for the additional gravitational pull of unseen dark matter. By careful studies of stellar motion, the group will improve measurements of the total mass present in nearby dwarf galaxies, and test whether they are being pulled apart by gravitational forces from neighbor galaxies. In more distant galaxies, they will measure motions of the surrounding globular star clusters to estimate the mass of the galaxy and hence of its dark matter. The group will collaborate with statisticians to analyze and interpret their results. The results of this work will test theories of galaxy formation, many of which predict that a galaxy must exceed a minimum mass in order to continue making stars. Students will be trained as they participate in the research. Both Dr Mateo and Dr. Olszewski will present public lectures on their work in their local communities. Through a program at U. Arizona, Dr. Olszewski will continue his work with elementary-school teachers, with star parties and visits to the Steward Observatory telescopes.